Electric-arc lamp.



Patented luly 23, l90l.

E. THOMSON.

ELECTRIC ARC LAMP.

No. 678,9l6.

(Application filed Dec. 26, 1899.)

(No Model.)

PATENT FFICE.

ELIHU THOMSON, OF SWAMPSCOTT, MASSCHUSETTS, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NEW YORK.

ELECTRIC-ARC LAM P.

SPEGEFEGATION forming part of Letters Patent No. 678,916, dated July 23, 1901. Application led December 26,1899. Serial No. 741,540. (No model.)

To a/ZZ whom t may concern:

Be it known that I, ELIHU THOMSON, a citizen of the United States, residing at Swampscott, county of Essex, State of Massachusetts,

have invented certain new and useful Improvements in Electric-Aro Lamps, (Case No. 1,090,) of which the following is a specification.

The present invention relates to electric- .lo arc lamps, and has for its object to improve their construction and operation.

In the accompanying drawings, which illustrate an embodiment of my invention, Figure l is asectional view of an arc-lamp. Fig.

I5 2 is a diagram of connections. Fig. 3 is a sectional view of the guide for the carbon-containing tube, taken on the line 3 3 of Fig. l. Figs. et and 5 are detail views of the uppercarbon holder. Figs. 6 and 7 are enlarged 2o views of the means employed to compensate for fluctuations in the line-current, and Figs. S and 9 are detail views of a modified form of carbon-holder.

The lamp-frame is composed of two vertical rods A, which are seated in the casting A at their upper end and are connected by the yoke A2 at their lower ends. Mounted in the yoke is a suitable holder-A3 for the arc-inclosing globe B and the lower carbon C.

3o Resting on the top of the inclosing globe is a gas-cap D, which may be of any suitable construction. The cap is provided with a oentral opening, and passing through this opening is the upper carbon or electrode C.. Surrounding the upper carbon 'is a tube E, and

on the lower end of the tube is a clutch F, the jaws of which are arranged to grasp the upper carbon and regulate the feeding thereof. To the upper end of the tube is secured a 4o dash-pot piston G, which works within the cylinder G. This dash-potis intended to check sudden movements of the upper carbon. Surrounding the carbon containing tube E is a tubular iron core or armature H, the upper extremity of which is tapered, so

that the actuating-magnet will exert a substantially even pull over a wide range of movement. For the purpose of guiding the tube E in its vertical movements small rollers 5o I are employed. These rollersare mounted in supports located above and below the ``Ward from the magnet-spool.

actuating-magnet, the upper rollers being mounted in a tubular piece I, having slots for receiving the rollers, and a bottom flange which rests on the top of the spool of the mag- 5 5 net and is secured thereto, while the bottom rollers are carried by a plate l2, which is secured to the projections I3, extending down- The rollers are of the shape shown in Fig. 3 and are located 6o in such a manner that the tube is permitted to move vertically with perfect freedom, but

is prevented from twisting out of line from any cause. In order to prevent undue friction between the parts, the piston G of the dash-pot is so connected to the tube E that a certain amount of lateral movement is permitted. lf desired, however, the connection between the dash-pot piston and tube maybe a rigid one and the cylinder G permitted to 7o move slightly in its support.

` It is Well known that after dilferential lamps have been in operation for a time more or less great certain changes in the pickup and feeding volt-ages occur. This is caused by the changes in resistance of the magnet-coils, whereby the proper relation or balance between them is more or less destroyed. Various attempts have been made heretofore to overcome this objection with 8o more or less success. In accordance with my invention the difficulties above referred to are overcome by providing an additional winding made of some metal having a low temperature coefficientas German silver,for example-which is connected around the series winding and works in opposition thereto, at the same time assisting the shunt-coil. Now as the resistance of the shunt and series coils increases more current will iiow 9o through the third winding and by proper adjustment as to length and cross-section may be made to compensate exactly for the decrease in effect of the shunt-coil, or it may be arranged to effect any other desired relation between the windings.

Referring to the drawings, J represents the compensating winding and is shown as being wound on a suitable spool, havinga dampingtube K for decreasing the iuctuations in 10o magnetism. Surrounding the compensating winding is the usual series winding L, and

outside of that is the usual shunt-winding M. The arrangement of these windings may be changed-that it to say, the compensating winding may be placed between the other two or on the outside, as desired. The upper and lower flanges of the magnet-spool are made of iron and forma part of the magnetic circuit. They are preferably connected magnetically outside of the windings. The connections of these windings are best shown in. Fig. 2. The series coil L is in series with the carbons and the arc, the shunt-coil M is connected across the terminals of the lamp, and the compensating coil J is connected at one end to the top of the series coil and at the other end to the bottom. The turns of the series winding are opposed to the turns of both the shunt and the compensating winding. The compensating winding being in shunt to a number of the series turns or to the entire series coil, more current will pass through the compensating winding after the series coil is heated, and the virtual effect thereof is to weaken the power of the series coil and in this way to compensate either wholly or in part for the weakened effect of a shunt-circuit winding as the lamp heats. The proportions between the various windings will vary considerably with the weight of the parts to be lifted and other details of construction, so that no set rule can begiven as to the relation between the ampere-turns of the various windings. This much can be said, however, that the change in the lifting effect of the series coil should be as nearly as possible equal to the change in effect of a shunt-winding due to heating. A skilled constructor will have no difficulty in adjusting the lamp for vpractical useful results.

In so-callec constant-current arc-light circuits, it sometimes happens that the current strength varies slightly from time to time.` The ordinary differential winding or arrangement of the lamp parts will to a certain extent compensate for these changes, but not entirely so. I propose to carry this compensation one step farther and to provide a regulator in addition to the ordinary lamp mechanism which will automatically maintain the current substantially Constantin the regulating-coils irrespective of changes in current strength. In carrying out this feature of my invention a shunt resistance is provided, which is connected around the series coil in such a manner that as the current in the line-circuit increases more or less of the current is shunted past the coil, but when the current decreases for any cause to a point below normal the effect of the shunt is decreased.

Referring to the drawings, N represents a magnet the winding o f which is connected in series with the series coil L. The connection of the magnet is best shown in Fig. 6, wherein N represents a frame-piece forming a support for a fixed electrode O. Pivotally supported by the frainepiece, but insulated therefrom, is an arm N2, in which is mounted an electrode O". .It is 'preferable to give the meeting faces of the electrodes a slight convexity, so that the extent of contact will be small. It is desirable, although not necessary, that a spring Ns be employed to hold the electrodes in contact'. The parts are preferably so constructed and arranged as to permita moderate percentage of the main current to be shunted past the series coil L at all times. When the current in the circuit increases, the magnet N attracts its armature with an increased force, thereby making better contact between the electrodes O and O, and more current is sh unted around the series coil L. On the other hand, when the amount of current in the circuit decreases the contact between the electrodes becomes poorer, and less current is shunted around the series coil. By this arrangement it is possible to relieve in a measure the disturbance which will oc cur in the length of the arc when the mainline current fluctuates, and by carefully proportioning and adjusting the parts variations in current strength of from twentyiive to thirty per cent. may be compensated for.

The carbon-holder for the upper carbon is best shown in Figs. and 5, wherein I represents a split metal sleeve which is arranged to hold the upper carbon C. Formed integral with or otherwise secured to the top of the sleeve is a rod P, having a cap l?2 secured to its upper end, and loosely mounted thereon is a number of beveled disks or cones P4. The top of the sleeve is beveled in a manner similar to the disks, and located between the disks is a number of small balls P3. As shown, a single row of balls is provided between the upper end of the sleeve and the first disk P", while between this disk and the second are two rows of balls and between the upper disk and the cap three rows of balls are shown. The disks IJ'L being provided with beveled or slanting surfaces on the top and bottom each disk furnishes bearingsurfaces for two rows of balls. The balls are mounted between the disks in such a manner that they are free to move and are made of some good conducting metal-as copper, for example. It is preferable .to heavily plate them with silver. It is also desirable to silver-plate the surfaces on which the balls travel, and I have found it desirable, although not necessary, to silver-plate the inside of the carboncontaining tube E. I do not consider the cones or disks essential elements of my invention, for they may be dispensed with and the space between the cap and the sleeve filled with balls; but they are useful in securing more perfect conductivity and in giving the balls regular positins, with a tend ency to move outward into engagement with the carbon-tube. The holder just described possesses many features of advantage, as it is simple to construct, insures many points IOO IIO

of contact between the tube and the carbon, and offers little opposition to the movements of the holder when the lamp is in operation.

In Figs. 8 and 9 a carbon-holder is shown having means for retaining the balls in place. This arrangement is desirable where it is necessary or desirable to remove the holder from time to time. The holder consists of a split sleeve, as before, and mounted on the rod P is a number of sheet-metal disks P4, each having beveled or slanting surfaces and fingers or projections P5, which extend between the balls for retaining them in place. Between the cap P2 and the upper disk P4 is a coiled spring P6, which tends at all times to force the disks together, thus moving the balls into engagement with the carbon-tube.

The lamp is provided with a mechanical cut-out Q and a magneticvcut-out R, both of which are of ordinary construction and work in the usual manner.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

1. In an electric-arc lamp, the combination of a movable tubular armature, shunt and series windings surrounding the armature, and a compensating winding also surrounding the armature, the coefficient of which differs from either the shunt or the series winding.

2. In an electric-arc lamp, the combination of upper and lower carbon electrodes,a shuntwinding, a series winding, and a compensating winding, which windings are concentrically disposed one over the other and surround the upper carbon; the compensating winding being arranged to form a shunt to the whole or a portion of the series winding, the last-mentioned windings having different coefficients.

3. In an electric-arc lamp, the combination of a carbon-tube, an armature surrounding the tube, a magnet-spool surrounding the tube and armature, a compensating winding mounted thereon, a series winding wound concentrically with respect to the iirst and connected in parallel relation thereto, and a third or compensating winding wound concentrically with respect to the other windings and acting on the armature and having a resistance and coefficient which differ from either of the windings.

4. In a constant-current-arc lamp, the combination of magnetic means for separating and feeding the carbons, a resistance path or circuit and means controlled by the current fiowing in the main-line circuit for shunting a part of the main-line current through the resistance path or circuit and past the said magnetic means when the current on the line rises and for decreasing the amount of the current so shunted when the main-line current falls below a certain point.

5. In an electric-arc lamp for constant-current'circuits, the combination of aseries coil for drawing the arc, a more or less imperfect shunt around the coil, and a magnetic means included in circuit with the series coil for varying this sh unt in accordance with changes of current in the main-line circuit.

6. In an electric-arc lamp, the combination of an armature which controls the feeding of an electrode, a coil which acts directly on the armature and is subjected to changes in current strength, a second coil which is in series with the iirst and is always in active service when the lamp is in operation, and automatic means controlled by the second coil for maintaining the current constant in the iirst-mentioned coil.

7. In an arc-lamp, the combination of differential windings, a regulating-magnet in series with one of the windings, and means controlled by the magnet for shunting more or less of the current around the winding which is connected in series with the regulating-magnet. Y

8. In an electric-arc lamp, the combinatio of a series-wound actuating-coil, a more or less imperfect shunt for the coil comprising two pieces of carbon, an arm for moving one piece of carbon with respect to the other, and a magnet included in the main circuit for moving the arm.

9. In a constant-current arc-lamp, the combination of an actuating-coil in series with the arc, a more or lessimperfect shunt around the coil, comprising carbon points, a spring for holding the points in contact, and a magnet included in the main circuit for assisting the spring in accordance with the current flowing in the arc-circuit.

IO. In a carbon-holder and contact device, the combination of a split sleeve, a rod secured thereto, beveled disks loosely mounted thereon and arranged in pairs with the beveled faces oppositely disposed, and rows of balls located between the disks and supported thereby.

11. Ina carbon-holder and contact device, the combination of means for holding the carbon, two or more beveled disks having projections or iingers formed integral therewith, and a row of balls located between the beveled disks and retained in place by the projections.

l2. In an electric-arc lamp, the combination of a carbon-containing tube, a dash-pot, a support for one element of the dash-pot which is secured to the magnet, a second element being secured to, and movable with the carbon-containing tube, the two elements being capable of adjustment with respect to each other, roller-guides mounted in the support and engaging with the upper end of the tube, and roller-guides mounted in a second and stationary support for engaging the lower end of the tube.

13. In an electric-arc lamp,the combination of a magnet having iron spool-flanges, eX- tensions on one of the flanges, a ring mounted on the iiange, and roller-guides which are carried by the ring.

14. In a differential arc-lamp, the combina- IOO IIO

'egg einem tion of a series winding, a shunt-Winding, 5 winding' and wound on the same core :is the and ai compensating winding which is active shunt-Winding, the shunt-Winding and the when the lmnp is in operation and is permitcompensating Winding being1 Wound in the nently connected in shunt around the series saine direction and therefore acting to assist I5 5 Winding and Wound on the seine spool with each other.

the shunt-winding. In witness whereof I have hereunto set my 15. In adifferentinl arehunp, the colnhinahand this 22d day of December, 1899. tion of a, series Winding, :t shunt-Winding, :i ELII-IU THOMSON. feeding mechanism acted upon differentially Witnesses: 1o by both of the windings, 2t compensating DUGALD MCKILLOP,

winding connected in shunt around the series HENRY O. VESTENDARP. 

